FFmpeg currently uses a custom build system, this text attempts to document

 some of its obscure features and options.
 

 Makefile variables:

 V
     Disable the default terse mode, the full command issued by make and its
     output will be shown on the screen.

 DBG
     Preprocess x86 external assembler files to a .dbg.asm file in the object

     directory, which then gets compiled. Helps in developing those assembler

     files.
 

 DESTDIR
     Destination directory for the install targets, useful to prepare packages

     or install FFmpeg in cross-environments.

 GEN
     Set to ‘1’ to generate the missing or mismatched references.
 

 Makefile targets:

 all
     Default target, builds all the libraries and the executables.

 fate

     Run the fate test suite, note that you must have installed it.

 
 fate-list

     List all fate/regression test targets.

 install
     Install headers, libraries and programs.

 examples
     Build all examples located in doc/examples.
 

 libavformat/output-example
     Build the libavformat basic example.

 libswscale/swscale-test

     Build the swscale self-test (useful also as an example).

 config

     Reconfigure the project with the current configuration.

 tools/target_dec_<decoder>_fuzzer
     Build fuzzer to fuzz the specified decoder.
 

 
 Useful standard make commands:
 make -t <target>

     Touch all files that otherwise would be built, this is useful to reduce
     unneeded rebuilding when changing headers, but note that you must force rebuilds

     of files that actually need it by hand then.
 
 make -j<num>

     Rebuild with multiple jobs at the same time. Faster on multi processor systems.

 
 make -k

     Continue build in case of errors, this is useful for the regression tests
     sometimes but note that it will still not run all reg tests.